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22a59be8b7
linux/net/sched/cls_api.c
Daniel Borkmann ea7f8277f9 net, cls: allow for deleting all filters for given parent 
Add a possibility where the user can just specify the parent and
all filters under that parent are then being purged. Currently,
for example for scripting, one needs to specify pref/prio to have
a well-defined number for 'tc filter del' command for addressing
the previously created instance or additionally filter handle in
case of priorities being the same. Improve usage by allowing the
option for tc to specify the parent and removing the whole chain
for that given parent.

Example usage after patch, no tc changes required:

  # tc qdisc replace dev foo clsact
  # tc filter add dev foo egress bpf da obj ./bpf.o
  # tc filter add dev foo egress bpf da obj ./bpf.o
  # tc filter show dev foo egress
  filter protocol all pref 49151 bpf
  filter protocol all pref 49151 bpf handle 0x1 bpf.o:[classifier] direct-action
  filter protocol all pref 49152 bpf
  filter protocol all pref 49152 bpf handle 0x1 bpf.o:[classifier] direct-action
  # tc filter del dev foo egress
  # tc filter show dev foo egress
  #

Previously, RTM_DELTFILTER requests with invalid prio of 0 were
rejected, so only netlink requests with RTM_NEWTFILTER and NLM_F_CREATE
flag were allowed where the kernel would auto-generate a pref/prio.
We can piggyback on that and use prio of 0 as a wildcard for
requests of RTM_DELTFILTER.

For notifying tc netlink monitoring users (e.g. libnl uses this
for caching), there are two options, that is, sending individual
tfilter_notify() notifications for each tcf_proto, or sending a
single one indicating wildcard removal. I tried both and there
are pros and cons for each, eventually I decided for sending
individual tfilter_notify(), so that user space can support this
seamlessly and there won't be a mess of changing each and every
application to make sure expectations from the kernel won't break
when they don't understand single notification. Since linear chains
don't really scale, I expect only a handful of classifiers to be
attached at max for a given parent anyway.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-10 18:11:01 -07:00

667 lines
15 KiB
C
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/*
* net/sched/cls_api.c Packet classifier API.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*
* Changes:
*
* Eduardo J. Blanco <ejbs@netlabs.com.uy> :990222: kmod support
*
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
/* The list of all installed classifier types */
static LIST_HEAD(tcf_proto_base);
/* Protects list of registered TC modules. It is pure SMP lock. */
static DEFINE_RWLOCK(cls_mod_lock);
/* Find classifier type by string name */
static const struct tcf_proto_ops *tcf_proto_lookup_ops(struct nlattr *kind)
{
const struct tcf_proto_ops *t, *res = NULL;
if (kind) {
read_lock(&cls_mod_lock);
list_for_each_entry(t, &tcf_proto_base, head) {
if (nla_strcmp(kind, t->kind) == 0) {
if (try_module_get(t->owner))
res = t;
break;
}
}
read_unlock(&cls_mod_lock);
}
return res;
}
/* Register(unregister) new classifier type */
int register_tcf_proto_ops(struct tcf_proto_ops *ops)
{
struct tcf_proto_ops *t;
int rc = -EEXIST;
write_lock(&cls_mod_lock);
list_for_each_entry(t, &tcf_proto_base, head)
if (!strcmp(ops->kind, t->kind))
goto out;
list_add_tail(&ops->head, &tcf_proto_base);
rc = 0;
out:
write_unlock(&cls_mod_lock);
return rc;
}
EXPORT_SYMBOL(register_tcf_proto_ops);
int unregister_tcf_proto_ops(struct tcf_proto_ops *ops)
{
struct tcf_proto_ops *t;
int rc = -ENOENT;
/* Wait for outstanding call_rcu()s, if any, from a
* tcf_proto_ops's destroy() handler.
*/
rcu_barrier();
write_lock(&cls_mod_lock);
list_for_each_entry(t, &tcf_proto_base, head) {
if (t == ops) {
list_del(&t->head);
rc = 0;
break;
}
}
write_unlock(&cls_mod_lock);
return rc;
}
EXPORT_SYMBOL(unregister_tcf_proto_ops);
static int tfilter_notify(struct net *net, struct sk_buff *oskb,
struct nlmsghdr *n, struct tcf_proto *tp,
unsigned long fh, int event);
static void tfilter_notify_chain(struct net *net, struct sk_buff *oskb,
struct nlmsghdr *n,
struct tcf_proto __rcu **chain, int event)
{
struct tcf_proto __rcu **it_chain;
struct tcf_proto *tp;
for (it_chain = chain; (tp = rtnl_dereference(*it_chain)) != NULL;
it_chain = &tp->next)
tfilter_notify(net, oskb, n, tp, 0, event);
}
/* Select new prio value from the range, managed by kernel. */
static inline u32 tcf_auto_prio(struct tcf_proto *tp)
{
u32 first = TC_H_MAKE(0xC0000000U, 0U);
if (tp)
first = tp->prio - 1;
return first;
}
/* Add/change/delete/get a filter node */
static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n)
{
struct net *net = sock_net(skb->sk);
struct nlattr *tca[TCA_MAX + 1];
struct tcmsg *t;
u32 protocol;
u32 prio;
u32 nprio;
u32 parent;
struct net_device *dev;
struct Qdisc *q;
struct tcf_proto __rcu **back;
struct tcf_proto __rcu **chain;
struct tcf_proto *tp;
const struct tcf_proto_ops *tp_ops;
const struct Qdisc_class_ops *cops;
unsigned long cl;
unsigned long fh;
int err;
int tp_created = 0;
if ((n->nlmsg_type != RTM_GETTFILTER) &&
!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
return -EPERM;
replay:
err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL);
if (err < 0)
return err;
t = nlmsg_data(n);
protocol = TC_H_MIN(t->tcm_info);
prio = TC_H_MAJ(t->tcm_info);
nprio = prio;
parent = t->tcm_parent;
cl = 0;
if (prio == 0) {
switch (n->nlmsg_type) {
case RTM_DELTFILTER:
if (protocol || t->tcm_handle)
return -ENOENT;
break;
case RTM_NEWTFILTER:
/* If no priority is provided by the user,
* we allocate one.
*/
if (n->nlmsg_flags & NLM_F_CREATE) {
prio = TC_H_MAKE(0x80000000U, 0U);
break;
}
/* fall-through */
default:
return -ENOENT;
}
}
/* Find head of filter chain. */
/* Find link */
dev = __dev_get_by_index(net, t->tcm_ifindex);
if (dev == NULL)
return -ENODEV;
/* Find qdisc */
if (!parent) {
q = dev->qdisc;
parent = q->handle;
} else {
q = qdisc_lookup(dev, TC_H_MAJ(t->tcm_parent));
if (q == NULL)
return -EINVAL;
}
/* Is it classful? */
cops = q->ops->cl_ops;
if (!cops)
return -EINVAL;
if (cops->tcf_chain == NULL)
return -EOPNOTSUPP;
/* Do we search for filter, attached to class? */
if (TC_H_MIN(parent)) {
cl = cops->get(q, parent);
if (cl == 0)
return -ENOENT;
}
/* And the last stroke */
chain = cops->tcf_chain(q, cl);
err = -EINVAL;
if (chain == NULL)
goto errout;
if (n->nlmsg_type == RTM_DELTFILTER && prio == 0) {
tfilter_notify_chain(net, skb, n, chain, RTM_DELTFILTER);
tcf_destroy_chain(chain);
err = 0;
goto errout;
}
/* Check the chain for existence of proto-tcf with this priority */
for (back = chain;
(tp = rtnl_dereference(*back)) != NULL;
back = &tp->next) {
if (tp->prio >= prio) {
if (tp->prio == prio) {
if (!nprio ||
(tp->protocol != protocol && protocol))
goto errout;
} else
tp = NULL;
break;
}
}
if (tp == NULL) {
/* Proto-tcf does not exist, create new one */
if (tca[TCA_KIND] == NULL || !protocol)
goto errout;
err = -ENOENT;
if (n->nlmsg_type != RTM_NEWTFILTER ||
!(n->nlmsg_flags & NLM_F_CREATE))
goto errout;
/* Create new proto tcf */
err = -ENOBUFS;
tp = kzalloc(sizeof(*tp), GFP_KERNEL);
if (tp == NULL)
goto errout;
err = -ENOENT;
tp_ops = tcf_proto_lookup_ops(tca[TCA_KIND]);
if (tp_ops == NULL) {
#ifdef CONFIG_MODULES
struct nlattr *kind = tca[TCA_KIND];
char name[IFNAMSIZ];
if (kind != NULL &&
nla_strlcpy(name, kind, IFNAMSIZ) < IFNAMSIZ) {
rtnl_unlock();
request_module("cls_%s", name);
rtnl_lock();
tp_ops = tcf_proto_lookup_ops(kind);
/* We dropped the RTNL semaphore in order to
* perform the module load. So, even if we
* succeeded in loading the module we have to
* replay the request. We indicate this using
* -EAGAIN.
*/
if (tp_ops != NULL) {
module_put(tp_ops->owner);
err = -EAGAIN;
}
}
#endif
kfree(tp);
goto errout;
}
tp->ops = tp_ops;
tp->protocol = protocol;
tp->prio = nprio ? :
TC_H_MAJ(tcf_auto_prio(rtnl_dereference(*back)));
tp->q = q;
tp->classify = tp_ops->classify;
tp->classid = parent;
err = tp_ops->init(tp);
if (err != 0) {
module_put(tp_ops->owner);
kfree(tp);
goto errout;
}
tp_created = 1;
} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind))
goto errout;
fh = tp->ops->get(tp, t->tcm_handle);
if (fh == 0) {
if (n->nlmsg_type == RTM_DELTFILTER && t->tcm_handle == 0) {
struct tcf_proto *next = rtnl_dereference(tp->next);
RCU_INIT_POINTER(*back, next);
tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);
tcf_destroy(tp, true);
err = 0;
goto errout;
}
err = -ENOENT;
if (n->nlmsg_type != RTM_NEWTFILTER ||
!(n->nlmsg_flags & NLM_F_CREATE))
goto errout;
} else {
switch (n->nlmsg_type) {
case RTM_NEWTFILTER:
err = -EEXIST;
if (n->nlmsg_flags & NLM_F_EXCL) {
if (tp_created)
tcf_destroy(tp, true);
goto errout;
}
break;
case RTM_DELTFILTER:
err = tp->ops->delete(tp, fh);
if (err == 0) {
struct tcf_proto *next = rtnl_dereference(tp->next);
tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);
if (tcf_destroy(tp, false))
RCU_INIT_POINTER(*back, next);
}
goto errout;
case RTM_GETTFILTER:
err = tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);
goto errout;
default:
err = -EINVAL;
goto errout;
}
}
err = tp->ops->change(net, skb, tp, cl, t->tcm_handle, tca, &fh,
n->nlmsg_flags & NLM_F_CREATE ? TCA_ACT_NOREPLACE : TCA_ACT_REPLACE);
if (err == 0) {
if (tp_created) {
RCU_INIT_POINTER(tp->next, rtnl_dereference(*back));
rcu_assign_pointer(*back, tp);
}
tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);
} else {
if (tp_created)
tcf_destroy(tp, true);
}
errout:
if (cl)
cops->put(q, cl);
if (err == -EAGAIN)
/* Replay the request. */
goto replay;
return err;
}
static int tcf_fill_node(struct net *net, struct sk_buff *skb,
struct tcf_proto *tp, unsigned long fh, u32 portid,
u32 seq, u16 flags, int event)
{
struct tcmsg *tcm;
struct nlmsghdr *nlh;
unsigned char *b = skb_tail_pointer(skb);
nlh = nlmsg_put(skb, portid, seq, event, sizeof(*tcm), flags);
if (!nlh)
goto out_nlmsg_trim;
tcm = nlmsg_data(nlh);
tcm->tcm_family = AF_UNSPEC;
tcm->tcm__pad1 = 0;
tcm->tcm__pad2 = 0;
tcm->tcm_ifindex = qdisc_dev(tp->q)->ifindex;
tcm->tcm_parent = tp->classid;
tcm->tcm_info = TC_H_MAKE(tp->prio, tp->protocol);
if (nla_put_string(skb, TCA_KIND, tp->ops->kind))
goto nla_put_failure;
tcm->tcm_handle = fh;
if (RTM_DELTFILTER != event) {
tcm->tcm_handle = 0;
if (tp->ops->dump && tp->ops->dump(net, tp, fh, skb, tcm) < 0)
goto nla_put_failure;
}
nlh->nlmsg_len = skb_tail_pointer(skb) - b;
return skb->len;
out_nlmsg_trim:
nla_put_failure:
nlmsg_trim(skb, b);
return -1;
}
static int tfilter_notify(struct net *net, struct sk_buff *oskb,
struct nlmsghdr *n, struct tcf_proto *tp,
unsigned long fh, int event)
{
struct sk_buff *skb;
u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
if (!skb)
return -ENOBUFS;
if (tcf_fill_node(net, skb, tp, fh, portid, n->nlmsg_seq, 0, event) <= 0) {
kfree_skb(skb);
return -EINVAL;
}
return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
n->nlmsg_flags & NLM_F_ECHO);
}
struct tcf_dump_args {
struct tcf_walker w;
struct sk_buff *skb;
struct netlink_callback *cb;
};
static int tcf_node_dump(struct tcf_proto *tp, unsigned long n,
struct tcf_walker *arg)
{
struct tcf_dump_args *a = (void *)arg;
struct net *net = sock_net(a->skb->sk);
return tcf_fill_node(net, a->skb, tp, n, NETLINK_CB(a->cb->skb).portid,
a->cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWTFILTER);
}
/* called with RTNL */
static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
int t;
int s_t;
struct net_device *dev;
struct Qdisc *q;
struct tcf_proto *tp, __rcu **chain;
struct tcmsg *tcm = nlmsg_data(cb->nlh);
unsigned long cl = 0;
const struct Qdisc_class_ops *cops;
struct tcf_dump_args arg;
if (nlmsg_len(cb->nlh) < sizeof(*tcm))
return skb->len;
dev = __dev_get_by_index(net, tcm->tcm_ifindex);
if (!dev)
return skb->len;
if (!tcm->tcm_parent)
q = dev->qdisc;
else
q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
if (!q)
goto out;
cops = q->ops->cl_ops;
if (!cops)
goto errout;
if (cops->tcf_chain == NULL)
goto errout;
if (TC_H_MIN(tcm->tcm_parent)) {
cl = cops->get(q, tcm->tcm_parent);
if (cl == 0)
goto errout;
}
chain = cops->tcf_chain(q, cl);
if (chain == NULL)
goto errout;
s_t = cb->args[0];
for (tp = rtnl_dereference(*chain), t = 0;
tp; tp = rtnl_dereference(tp->next), t++) {
if (t < s_t)
continue;
if (TC_H_MAJ(tcm->tcm_info) &&
TC_H_MAJ(tcm->tcm_info) != tp->prio)
continue;
if (TC_H_MIN(tcm->tcm_info) &&
TC_H_MIN(tcm->tcm_info) != tp->protocol)
continue;
if (t > s_t)
memset(&cb->args[1], 0,
sizeof(cb->args)-sizeof(cb->args[0]));
if (cb->args[1] == 0) {
if (tcf_fill_node(net, skb, tp, 0,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, NLM_F_MULTI,
RTM_NEWTFILTER) <= 0)
break;
cb->args[1] = 1;
}
if (tp->ops->walk == NULL)
continue;
arg.w.fn = tcf_node_dump;
arg.skb = skb;
arg.cb = cb;
arg.w.stop = 0;
arg.w.skip = cb->args[1] - 1;
arg.w.count = 0;
tp->ops->walk(tp, &arg.w);
cb->args[1] = arg.w.count + 1;
if (arg.w.stop)
break;
}
cb->args[0] = t;
errout:
if (cl)
cops->put(q, cl);
out:
return skb->len;
}
void tcf_exts_destroy(struct tcf_exts *exts)
{
#ifdef CONFIG_NET_CLS_ACT
tcf_action_destroy(&exts->actions, TCA_ACT_UNBIND);
INIT_LIST_HEAD(&exts->actions);
#endif
}
EXPORT_SYMBOL(tcf_exts_destroy);
int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb,
struct nlattr *rate_tlv, struct tcf_exts *exts, bool ovr)
{
#ifdef CONFIG_NET_CLS_ACT
{
struct tc_action *act;
INIT_LIST_HEAD(&exts->actions);
if (exts->police && tb[exts->police]) {
act = tcf_action_init_1(net, tb[exts->police], rate_tlv,
"police", ovr,
TCA_ACT_BIND);
if (IS_ERR(act))
return PTR_ERR(act);
act->type = exts->type = TCA_OLD_COMPAT;
list_add(&act->list, &exts->actions);
} else if (exts->action && tb[exts->action]) {
int err;
err = tcf_action_init(net, tb[exts->action], rate_tlv,
NULL, ovr,
TCA_ACT_BIND, &exts->actions);
if (err)
return err;
}
}
#else
if ((exts->action && tb[exts->action]) ||
(exts->police && tb[exts->police]))
return -EOPNOTSUPP;
#endif
return 0;
}
EXPORT_SYMBOL(tcf_exts_validate);
void tcf_exts_change(struct tcf_proto *tp, struct tcf_exts *dst,
struct tcf_exts *src)
{
#ifdef CONFIG_NET_CLS_ACT
LIST_HEAD(tmp);
tcf_tree_lock(tp);
list_splice_init(&dst->actions, &tmp);
list_splice(&src->actions, &dst->actions);
dst->type = src->type;
tcf_tree_unlock(tp);
tcf_action_destroy(&tmp, TCA_ACT_UNBIND);
#endif
}
EXPORT_SYMBOL(tcf_exts_change);
#define tcf_exts_first_act(ext) \
list_first_entry_or_null(&(exts)->actions, \
struct tc_action, list)
int tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts)
{
#ifdef CONFIG_NET_CLS_ACT
struct nlattr *nest;
if (exts->action && !list_empty(&exts->actions)) {
/*
* again for backward compatible mode - we want
* to work with both old and new modes of entering
* tc data even if iproute2 was newer - jhs
*/
if (exts->type != TCA_OLD_COMPAT) {
nest = nla_nest_start(skb, exts->action);
if (nest == NULL)
goto nla_put_failure;
if (tcf_action_dump(skb, &exts->actions, 0, 0) < 0)
goto nla_put_failure;
nla_nest_end(skb, nest);
} else if (exts->police) {
struct tc_action *act = tcf_exts_first_act(exts);
nest = nla_nest_start(skb, exts->police);
if (nest == NULL || !act)
goto nla_put_failure;
if (tcf_action_dump_old(skb, act, 0, 0) < 0)
goto nla_put_failure;
nla_nest_end(skb, nest);
}
}
return 0;
nla_put_failure:
nla_nest_cancel(skb, nest);
return -1;
#else
return 0;
#endif
}
EXPORT_SYMBOL(tcf_exts_dump);
int tcf_exts_dump_stats(struct sk_buff *skb, struct tcf_exts *exts)
{
#ifdef CONFIG_NET_CLS_ACT
struct tc_action *a = tcf_exts_first_act(exts);
if (a != NULL && tcf_action_copy_stats(skb, a, 1) < 0)
return -1;
#endif
return 0;
}
EXPORT_SYMBOL(tcf_exts_dump_stats);
static int __init tc_filter_init(void)
{
rtnl_register(PF_UNSPEC, RTM_NEWTFILTER, tc_ctl_tfilter, NULL, NULL);
rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_ctl_tfilter, NULL, NULL);
rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_ctl_tfilter,
tc_dump_tfilter, NULL);
return 0;
}
subsys_initcall(tc_filter_init);
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